Edge accuracy in a capacitive sense array

Abstract

A capacitive sense array configured to improve edge accuracy in detecting a presence of a conductive object is described. In one embodiment, a capacitive sense array includes at least a first set of sense elements having non-homogenous pitches disposes in a first longitudinal axis of the capacitive sense array. The pitch includes width of the sense elements and spacing between the sense elements.

Description

RELATED APPLICATIONS[0001]This application claims the benefit of PCT / US11 / 48908, IP / US filed on 24 Aug. 2011.TECHNICAL FIELD[0002]This disclosure relates to the field of user interface devices and, in particular, to capacitive sense devices.BACKGROUND[0003]Capacitive sense arrays may be used to replace mechanical buttons, knobs and other similar mechanical user interface controls. The use of a capacitive sense element allows for the elimination of complicated mechanical switches and buttons, providing reliable operation under harsh conditions. In addition, capacitive sense elements are widely used in modern customer applications, providing new user interface options in existing products. Capacitive sense elements can be arranged in the form of a capacitive sense array for a touch-sensing surface. When a conductive object, such as a finger, comes in contact or close proximity with the touch-sensing surface, the capacitance of one or more capacitive touch sense elements changes. The c...

AI Technical Summary

Benefits of technology

This patent is about a new design for capacitive sense devices that can be used in user interface devices. The new design solves a problem with traditional designs where there is a significant difference in accuracy between the center and edge areas of the device. The new design uses non-homogenous pitch sensors, which means that the sensors have different sensor widths. This new design improves accuracy and allows for better tracking of user input.

Problems solved by technology

However, conventional designs exhibit considerable position tracking error near the edges of the touch screen.

One problem with this conventional design is that accuracy variation between a center area and an edge area.

So, without a complete signal profile, the centroid determination of the finger would certainly have some error in the centroid algorithm since the information is unbalanced, resulting in systematic centroid offset along the edges of the panel.

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